Elon Talking Rocket Engines with Tim Dodd
To kick it off, a video by Tim Dodd from 2019, where he explains how rocket engines work and how the Raptor for Starship compares to other engines and generally achieves a lot of firsts in its domain:
Is SpaceX's Raptor engine the king of rocket engines?
The Raptor architecture is the highes efficiency rocket engine know to physics, according to Musk. It achieves combustion efficiency of 99%.
Another helpful video by Tim on rocket enine cooling: Why don't rocket engines melt? How engineers keep engines cool
And another. This time about engine cycles: Rocket engine cycles: How do you power a rocket engine?
Now to the meat:
Deleting Parts as Engineering Principle
Elon explains the vast improvements they managed to achieve, by pointing out how complex the first version looked in comparison with version two. They achieved most of it by eliminating parts, because according to Elon:
"The single biggest mistake an intelligent engineer makes, is to optimize a thing that shouldn't exist".
"If you are not adding back at least 10% of the things you are deleting, you are not deleting enough."
Deleting is one tenent of Musk's engineering philosophy.
A large part in simplifying was to get rid of main chamber torch igniters. How they did it is "secret sauce".
Elon wants to get rid of enough sensitive engine features, so that shrouds for protection against heat, aren't required anymore.
Iterating Fast as Engineering Principle
"Technology development is how many iterations you have and time and progress between iterations."
A high production rate allows for many iterations and allows to experiment often. Failure is acceptable, because the next unit will soon be ready.
A high production rate cures many ills.
Apart from all the improvements the Raptor engine offers, they are also trying to get rid of hydraulic actutators for steering the nozzle.
A hydraulic system made sense for the Falcon 9, because the working fluid for the Merlin engine is pressurised Kerosene. It is perfectly fine to use it as a hydraulic fluid as well.
For a methane based engine, there needs to be a completely separate system. SpaceX wants to avoid extra complexity and mass. The solution is electric screwdrives. In part because the hydraulic system already needs batteries and electric motors. Deleting the hydraulic system and replacing it with powerful servo motors makes sense.
SpaceX was always focused on increasing chamber pressure. This is the inside baseball of rocket engines, according to Elon.
Usually, the main criteria for rocket engines is ISP (specific impulse), but it should be "Area under the Force-Time curve for a given mass flow". The reason is that to get to ISP, there are a lot of simplifications and assumptions.
Where they are currently conservative is on the film cooling side. Excessive cooling affects engine efficiency, but it keeps engines from melting. Fine-tuning can be done at a later date.
Addendum: Elon talking to Tim about the Merlin Engine, which powers the Falcon 9 rocket: Elon Musk Explains SpaceX's Merlin Engine!
Starlink 3 - 1
SpaceX is launching 46 additional Satellites for their own Starlink Constellation.
It is the 1st batch of satellites for the 3rd layer of the constellation. Shell 3 is in a 560km circular low-Earth orbit. These satellites are equiped with laser links.
The booster is a Block 5 and will land on a drone ship. It is on its 6th mission and it took 58 days to turn around from the last mission.
The mission to low earth orbit will launch from andenberg Space Force Base, California and land on a barge.
- Payload mass is approximately 14 tonnes
- 46 Starlink Satellites
Check your local time of launch at: www.timeanddate.com
Where to watch:
- 15 minutes before launch: SpaceX Livestream
Background information about previous SpaceX launches: Wikipedia
Starlink availability world map
Scott Manley: SpaceX's 'Wet' Fleet 2021
Why SpaceX is Making Starlink - Real Engineering: Youtube
Ellie in Space: Does SpaceX's Starlink have a first mover advantage against competitors like Amazon?
MikeOnSpace: OFFICIAL Starlink SPEED TEST results and SPACE LASERS - details on the Private Beta and Public Beta
Mark Handley: Using ground relays with Starlink
MikeOnSpace: Amazon KUIPER vs SpaceX STARLINK - Another heavyweight enters the race for Global Satellite Internet
Ben Sullins: Starlink Could Change EVERYTHING!
LTT: Gaming on STARLINK!!
Now You Know: We Test Elon’s $99 Mobile Internet | In Depth
Mediocre Coffee: Starlink vs. Telus: My Experience in Rural Alberta
Scott Manley: Graveyard Orbits Where Old Satellites Are Forgotten
Useful links to stay up to date on launches:
Spaceflightnow.com: Launch Schedule
Everyday Astronaut: Prelaunch Previews
NASA Spaceflight nasaspacefight.com
Track Starlink satellites: https://satellitemap.space/
Vote for my witness: @blue-witness
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